Update Rollup 2 for Exchange Server 2007 (KB935490)
"Update Rollup 2 for Exchange Server 2007 resolves issues that were found in Exchange Server 2007 since the software was released. This update rollup is highly recommended for all Exchange Server 2007 customers."
If you already downloaded the patch that corrects the Exchange 2007 vulnerability mentioned on the previous post, you noticed that it corresponds to a new Update Rollup.
No, Microsoft will not release a new rollup every 3 weeks, they only did it this time because of the security issue. For a list of the included fixes, please read the Knowledge Base article Description of Update Rollup 2 for Exchange 2007.